Volumetric Compressive Oscillometry for Cardiac Output Evaluation

Introduction. The study discusses different techniques proposed for cardiac output assessment. One of them is a non-invasive volumetric compressive oscillometry (VCO). VCO bases on measurements of the blood volume change under an inflatable cuff around an extremity. VCO determines blood pressure by recording the volumetric arterial oscillograms allowing speed and character of pulse-wave increase and decrease evaluation, and judgment about heart pump condition and vascular walls elasticity. Objectives. To compare the heart pump capacity determined by two different techniques: classical pre-pulmonary thermodilution and VCO. Materials and methods. Seven intensive care unit patients in early postoperative periods after open-heart surgery were included. Two hundreds parallel measurements of cardiac output (CO) performed during several days. One hundred by the pre-pulmonary thermodilution techniques with catheter Swan-Ganz in pulmonary artery (CareScape monitor B850, GE Healthcare), and one hundred by the VCO (Multimodal monitor 6-03, Triton, Russia). The data showed as CO and cardiac index (CI) — CO divided by the body surface area. For statistical analysis calculated mean error, received data displayed by Bland—Altman plot. Results. CO and CI figures were found to be comparable: 5.41 ± 0.12 & 5.33 ± 0.13 l∙min–1, and 2.93 ± 0.13 & 2.92 ± 0.94 l∙min–1∙м–2, correspondingly. Mean error for CO and CI was about 10 %. VCO overvaluation of CO and CI relatively to thermodilution was 11.1 ± 1.2 & 9.6 ± 1.1 %; undervaluation — 10.8 ± 1.3 & 12.1 ± 1.3 %, correspondingly. Conclusion. Volumetric compressive oscillometry can be safely used for CO measurement in cardio-surgical patients. Researcher should keep in mind limitations of any technique based on the pulse-way analysis.